1. Field of Invention
The invention relates to the technical field of a surface-modified composite solid particle and a method for producing the same.
2. Description of Related Art
There has so far been known in, for example, U.S. Pat. No. 4,915,987, a production process for a composite solid particle for the purposes of preventing coagulation, discoloration and deterioration and elevating dispersibility, catalytic effect and magnetic characteristics by fixing fine particles (hereinafter referred to as fine particles) on the surface of another particle which becomes a core (hereinafter referred to as a core particle). It has become possible to efficiently produce a functional composite or hybrid powder material (composite or hybrid powder) which is homogeneous and has stable characteristics by employing a high velocity gas stream impact method which is a dry particle compositing method requiring no organic solvent and no water, which is described therein.
However, in the composite solid particle produced by the method described above, the fine particles are merely stuck evenly on the surface of the core particle, and therefore a rough weight proportion of the fine particles exerting influence on an improvement in the functionality to the core particle depends on the surface area of the core particle and the cross section (projected area) of the fine particle. In general, it is considered that the maximum weight proportion of the fine particles to the core particle is a proportion in which the fine particles cover the surface of the core particle only in roughly one layer. Thus, the maximum weight proportion of the fine particles to the core particle is calculated from: EQU maximum weight proportion=(4r.rho.1/R.rho.0).times.100%
where: r=radius of the fine particle
R=radius of the core particle PA2 .rho.1=density of the fine particle PA2 .rho.0=density of the core particle
As a result thereof, if the radii and the densities of the core particle and the fine particles are fixed, the maximum weight proportion of the fine particles is settled, and the weight proportion exceeding this cannot be achieved, which brings about the problem that little further elevation in the function can be expected. Thus, the problem to be solved by the invention is addressed to this point.